Process for removing heavy metals from petroleum with an oil-insoluble sulfonic acid



i RocE ss FOR REMOVING HEAVY METALS FROM PETROLEUM WITH AN OIL-INSOLUBLESULFONIC A'CID Everett N. Case, Homewood, and Robert Koncos, ParkForest, Ill.,, ,assig'nors to Sinclair Refining Company, New York, N.Y.,a corporation of Maine No Drawing. Filed Dec. 29, 1958, Ser. No. 783,148

3 Claims. (Cl. 2082'52) This invention relates to a process for removingheavy metal contaminants from petroleum. More particularly, theinvention involves a process for effectively reducing the vanadium andnickel contents of heavy hydrocarbons such as crude petroleum and itsresidual fractions.

Metal contaminants, particularly vanadium and nickel are present inalmost all crude petroleum in the form of hydrocarbon-solublemetallo-organic complex nitrogen compounds. The concentration of themetal contaminants varies widely with the source of the stock but isvery small, that is, in the order of parts per million. Because of thevery small concentration of the metal contaminants, their removal fromthe residual stock is extremely difficult.

Attention has been focused on the necessity of removing metalcontaminants from petroleum by the almost universal adoption ofcatalytic cracking for the production of high octane gasoline. Thepresence of metal contaminants particularly vanadium and nickel in thecracking hydrocarbon charge stock obtained from crude or residualpetroleum fractions not only seriously shortens the life of crackingcatalysts but also changes the selectivity of the catalysts with theresult that more of the hydrocarbon charge is converted to carbon and togas. In addition to their harmful action on cracking catalysts whenpresent in the cracking charge, metal contaminants present in residualoils cause pitting corrosion of turbine blades and fuel oil burners.

Present procedures for removing metal contaminants from petroleum eitherresult in a substantial loss of hydrocarbon or concentrate themetal-containing compounds in a particular fraction. One of the meanspresently used to free cracking charges of metal contaminants involvesdistillation of the fraction or its source material under conditionswhich prevent entrainment of the high boiling metal-containing nitrogencomplexes with the result that the metal contaminants concentrate in theresidual fractions and cause pitting and corrosion of burners when thelatter are utilized as fuel.

It has now been found that heavy metals such as nickel and/ or vanadiumcontaminants can be removed from petroleum crude or residual fractionsthereof by treatment in the liquid phase with oil-insoluble aromaticsulfonic acids which are liquids at the treating temperature. Thesesulfonic acids are usually of benzenoid hydrocarbons containing one ormore lower alkyl or lower cycloalkyl radicals. Representative sulfonicacids are those of mixed meta and xylenes, toluene, an aromaticreformate fraction in the C to C range, etc. or mixtures thereof. Thearomatic hydrocarbon which is used to provide the sulfonic acid ispreferably in the gasoline boiling range and is frequently composedpredominantly of methyl and ethyl-substituted benzenes. Some of ourmetal contaminated hydrocarbon charge stocks may contain water, say upto about so we prefer to employ water-soluble sulfonic acids that willtates atrt 0 "ice not precipitate as solids in the presence of thecontaminating water. It is also preferred to employ the anhydrous formof sulfonic acids although sulfonic acids having up to about 10% byweight of water have been successfully used. We have observedessentially no chemical reaction between the sulfonic acid and thehydrocarbon treated. Also in addition to obtaining demetallization byour process there is evidence that desalting, denitriding and possiblydesulfurization of the hydrocarbon are effected and the treated materialor a distillate therefrom exhibits less carbon-forming tendencies whensubsequently cracked.

In accordance with the present invention a crude petroleum or residualfraction thereof containing contaminating amounts of nickel and vanadiumis intimately contacted with the sulfonic acid in amounts suflicient toremove a substantial portion of the nickel and vanadium contaminants ata temperature up to about 150 F. for instance, within the range of about50 to 150 F. Temperatures materially above about 150 are not desirablesince loss :of the sulfonic acids results through reaction with thefeedstock. Room or ambient temperatures are normally used and producesatisfactory results. The sulfonic acid-feedstock mixture can then beallowed to settle into two immiscible phases, a feedstock ratfinatelayer and a precipitate layer. After setting is complete, thedemetallized feedstock raflinate layer can be decanted from theprecipitated sulfonic acid phase.

The amount of the sulfonic acid of the present invention contacted withthe feedstock'is that; sufficient to remove a substantial portion of thenickel and vanadium contaminants contained in the feedstock and theamount exceeds the portion which might be compatible with thehydrocarbon treated. Generally, amounts ranging from about 1 to 30 ormore, preferably about 5 to 15, weight percent based on the contaminatedhydrocarbon feedstock are employed and have been' found sufiicient.Similarly the contact and settling times may be varied over aconsiderable range. A contact time of aboutonehalf hour has been foundsutficient and settling; has been found substantially complete afterabout 24v hours.

The process of the invention can be applied to;v crude. petroleum or toresidual fractions thereof" which fre quently contain up to about 1000ppm. of contaminating,- metals. Representative stocks are, for example,crude: petroleum (25-100 p.p.m.), atmospheric towerbottoms (-200p.p.m.), vacuum tower bottoms (500-1000 p.p.m.'), oil from deoilingvacuum towerb0;ttoms -or from deasphalting vacuumtower bottoms(2+400;p.p,m.), hydrocracked residuals and thermally cracked residuals.Because of difficulties presented in the handling of many of thefeedstocks to which the present invention is applicable, it has beenfound advantageous to dilute these feedstocks with a suitablehydrocarbon solvent, for instance, an aliphatic hydrocarbon of about 3to 7 carbon atoms. Frequently, the solvent volume is about 0.1 to 10 ormore times that of the contaminated hydrocarbon. Crude petroleum on theother hand, presents no handling problems and therefore needs nodilution.

The process of the present invention will be further illustrated by thefollowing examples but they are not to be considered limiting.

EXAMPLE I 1500 ml. of Kuwait crude petroleum containing 20 ppm. of NiOand 46 p.p.m. of V 0 was charged to a 2-liter flask equipped with astirrer. Stirring was started and 60 grams of liquid, mixed xylene andethyl benzene sulfonic acids (11% para, 49% meta, 16% ortho, 24% C H -CH were added. Stirring was com tinned for one-half hour and the mixturewas allowed to settle. Settling was substantially complete in about 24hours and resulted in the formation of a precipitate layer and araflinate layer. The raflinate was decanted from the precipitate layer,washed with water and analyzed for M and V 0 content. The approximatevolume of raflinate obtained from the decanting was 1100 ml. Therafiinate was again treated with the same amount of the xylene sulfonicacids and the raflinate of the second treatment similarly analyzed forNiO and V 0 content.

The above experiment was repeated using toluene sulfonic acid. Theresults of the raflinate analyses are shown in Table I.

Table I EXAMPLE II An atmospheric tower bottoms having a carbon residueof 7.46 and containing 49 p.p.m. of MO and 100 p.p.m. of V 0 was chargedto each of six 2-liter flask equipped with a stirrer. Stirring wasstarted and amounts ranging from 2 to 6.7 weight percent of mixed xylenesul fonic acids were added immediately followed by various volumes ofpentane. Stirring was continued for onehalf hour and the mixture wasallowed to settle two days. At the end of the settling period thesolvent-crude mixture was decanted from the precipitate layer. Theprecipitate was weighed and then the dissolved pentane was removed undervacuum at room temperature to a constant weight. The pentane-freeprecipitate was dissolved in benzene and the solution washed with fourportions of water. The water washes were titrated with sodium hydroxidesolution to determine the percent xylene sulfonic acids in theprecipitate. The water washed benzene solution was evaporated down on ahot plate to a terminal temperature of 320 F. The residue was thensubmitted for percent pentane soluble.

The crude pentane solution decanted from the sulfonic acid-precipitatelayer was washed with proportions of water which were also titrated togive the acid content of the crude layer. The washed pentane solutionwas evaporated down on a hot plate to a terminal temperature at 320 F.The residue was then analyzed for metal and carbon residue.

The results obtained from these experiments are tabulated in Table 11.

4 Table II Experiment 1 Ratio by volume pentane/ATE. 5 Wt. percentxylene sulfonic acid on ATB Extract Layer:

Wt. percent yield on ATB Wt. percent pentane b Wt. percent xylenesulfonic acid b 5. Percent Pentane soluble 7 Raflinate layer:

Wt. percent pentane Wt. gercent xylene sull'onic ac Wt. percent carbonresidue p.p.m. V O5' Calculated on a pentane and xylene sulfonic acidfree basis.

Percent based on total precipitate weight.

a Determined on xylene sulfonic acid and pentane-free residue.

Determined by Com-adson method on xylene sulfonlc acid and pentane treeoil.

- Determined on xylene sulionic acid and pentane tree oil:

ATB-earbouresidue 7.46 NiO 13% Examination of the data clearlydemonstrates the effectiveness of the process of the present inventionin removing vanadium and nickel contaminants from crude petroleum andreduced crudes.

We claim:

1. In a process for demetallizing a heavy metal containing heavyhydrocarbon, the steps comprising contacting said hydrocarbon with aliquid, oil-insoluble aromatic sulfonic acid at a temperature of up toabout F. in an amount sutficient to reduce the heavy metals content ofsaid hydrocarbon and separating a hydrocarbon phase reduced in heavymetal content from a sulfonic acid phase.

2. In a process for demetallizing a petroleum hydrocarbon containingnickel and vanadium and selected from the group consisting of crudepetroleum and its residual fractions, the steps comprising intimatelycontacting said hydrocarbon with a liquid, oil-insoluble, water-solublebenzenoid sulfonic acid at' a temperature of up to about 150 F. in anamount of about 1 to 30% based on said hydrocarbon, setting thecontacted mixture, and separating a hydrocarbon phase reduced in nickeland vanadium contents from a sulfonic acid phase.

3. The method of claim 2 in which the sulfonic acid is a mixture ofortho, meta, para, xylene and ethylbenzene sulfonic acids.

Archibald May 9, 1939 Gilbert June 12, 1951

1. IN A PROCESS FOR DEMETALLIZING A HEAVY METAL CONTAINING HEAVYHYDROCARBON, THE STEPS COMPRISING CONTACTING SID HYDROCARBON WITH ALIQUID, OIL-INSOLUBLE AROMATIC SULFONIC ACID AT A TEMPERATURE OF UP TOABOUT 150* F. IN AN AMOUNT SUFFICIENT TO REDUCE THE HEAVY METALS CONTENTOF SAID HYDROCARBON AND SEPARATING A HYDROCARBON PHASE REDUCED IN HEAVYMETAL CONTENT FROM A SULFONIC ACID PHASE.